netdev - Re: [PATCH net-next 5/5] net: mvneta: allocate TSO header DMA memory in chunks

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Date: Wed, 10 May 2023 13:38:17 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Cc: Marek Behún <kabel@...nel.org>, 
	"David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org, 
	Paolo Abeni <pabeni@...hat.com>, Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH net-next 5/5] net: mvneta: allocate TSO header DMA memory
 in chunks

On Wed, May 10, 2023 at 12:16 PM Russell King (Oracle)
<rmk+kernel@...linux.org.uk> wrote:
>
> Now that we no longer need to check whether the DMA address is within
> the TSO header DMA memory range for the queue, we can allocate the TSO
> header DMA memory in chunks rather than one contiguous order-6 chunk,
> which can stress the kernel's memory subsystems to allocate.
>
> Instead, use order-1 (8k) allocations, which will result in 32 order-1
> pages containing 32 TSO headers.

I guess there is no IOMMU/SMMU/IOTLB involved on platforms using this driver.

(Otherwise, attempting high-order allocations, then fallback to
low-order allocations
would provide better performance if the high-order allocation at init
time succeeded)

Reviewed-by: Eric Dumazet<edumazet@...gle.com>

Thanks